Trailing net



Mayl lz, 192s. 1,537,416 R. DE BOER ET AL TRAILING NET Filed ApriPatented May 12, 1925.

UNITED STATES PATENT OFFICE.

ROELOF DE BOER AND HENRI WILLEM DE VOOGT, OF HEEMSTEDE, NETHERLANDS.

TRAIKLING NET.

Application filed April 11, 1924. Serial No. 705,921.

T0 all whom t may concern.'

Be it known that we, ROELOE DE BOER and HENRI WILLEM DE Vooc'r, bothsubjects of the Queen of the Netherlands, residing at Heemstede, theNetherlands, have invented certain new and useful Improvements inTrailing Nets, of which the following is a specification.

The invention relates to trailing nets and particularly to such nets towhich by aspecial construction it is attempted to give a high and widemouth opening.

Although the fundamental idea of the invention and the constructionresulting there from relate to trailing` nets along the ground (trawlnets) as well as to trailing nets which may be used along the surface orat an arbitrary depth beneath the surface, the following descriptionwill deal more particularly with trawl nets. In the numerous embodinients of trawl nets in which it is attempted to hold up a wideupper cable by floating bodies and thus incre-ase the height of themouth opening, the fact that the distance of the sheering boards (mouthwidth) is influenced by the forces acting in the vertical plane of themouth opening and those acting in a horizontal plane has notsuflicieiitly been taken into account.

In a vertical plane through the upper cable and sheei'ing boards a stateof equilibrium arises between the forces in this plane acting on thefloating bodies and on the sheering boards. i

In constructing the boards and corresponding floating bodies it istherefore of great importance to take into consideration the variousforces acting on both in such a manner that the floating bodies at thenormal speed come to stand perpendicularly above the boards.

The mutual distance of the floating bodies should determine as well aspossible the distance between the corresponding sheeriiig boards or theobtainable sheering width of the net. A single or more than'two strongfloating bodies arranged on the upper cable or the location of theselfloating bodies near the centre gives rise to an action of the net whichis undesirable for the fishery.

In the horizontal plane through the sheeralso on the lengthV of theground and upper cable.

The invention has for its object to construct a trailing net having avery wide mouth opening at the normal speed, on the one hand by choosingthe point of application of the resistance of the net and the catchbehind the boards in such a manner that the component of thisresistance, nie-asured on the line connecting the boards, is as small aspossible and, on the other hand, by connecting the floating bodies tothe wide upper cable at the correct distance with regard to the sheeringboa-rds.

The invention consists in this, that two waists are provided, thevertical central planes of which are parallel or almost paiallel to eachother and to the trailiiigdirection of the net and which central planespass through the connecting points of the net to the sheering boards orintersect the connecting line of these boards at a mutual distancesmaller than that of the boards.

Now, according to the invention each waist may be connected by separatecarrying lines to the sheering boards located in front of it. In thisway, when trailing the net, the resistance caused by the waist in thewater is almost entirely received by the trailing line.

Moreover the meshes of the net leading to the waist are now notcontracted when the waist is lled with fish and therefore the resistanceof the net in the water is not increased. The inflowing water can easilyescape through the open meshes. The net itself needs no more transmitthe resistance of the waist to the sheeriiig boards but the cableseffect this and the net is not deformed.

Another feature of the invention consists in this, that the two waistsare interconnected by a connecting line at the upper side of the net anda connecting line at the lower side, while on each of these connectinglines two points are connected to the sheering boards by upper andground cable respectively. y

The two connecting points of the connecting line with the upper cablemay be provided with small floating bodies for lifting the back net.

Further, with a net of this kind, between the two sheering boards asecond Ywide upper cable may be stretched to which two floating bodiesare connected determini-ng the mutual distance of the sheering board atthe normal trailing speed.

By this construction, when trail-ing the net an almost rectangular mouthopening is formed; the tension in the horizontal portion of the cablebetween the two floating bodies and the horizontal component of theupdriving force of these floating bodies balances the sheering :torce ofthe boards.

Between the wide upper cable and the back net, according to theinvention convenient catching nets may be'stretched while the floatingbodies a-re preferably trailedV by branch lines of the net trailinglines.

In order tov make the net appropriate for trawling on stony (rocky)grounds according to the invention the net may be provided at the lowerside with a pocket merging backwardly and laterally into the two waistsand limited at the front side by a ground "i rope which may be providedwith rolls or bobbins.

This modiiicationof the net may be used as well for trawling herrings.In this case it is only desired to remove the bobbins from the groundyrope and to suspend the net from surface floating bodies.

By shortening or lengthening the suspenA sion lines the depth of the netbelow the surface of the water can be adjusted'.

In the accompanying drawings, a trailing net according to the invention,constructed as a trawl net, is shown by way of example.

Figure 1 is aplan view of the net;

Figure 2 is a verticallongitudinal section, and' Figure 3 a frontelevation.l Fig. 4 is a vertical longitudinal section ot the net withpocket at the lower side for trawling herrings or for lishing on stonygrounds.

Fig. 5 is a front elevation of' thisnet.

The whole net is built up from a. skeleton of carrying lines. The twowaists 1 and 2 are each connected to the sheering boards 3 and 4respectively by 'four carrying' lines., The waist 1 is connected at theupper side by the lines 5 and 6 to the upper sfide ofthe sheeringyboard13 and by the lines 7 and 8 to the lower side of this sheeringboard. In a similar manner the lines 9, 10,

11 and 12 constitute the carrying lines for the waist 2.

Mutually the waists are connected at the lower and upper sides by twoconnecting lines that are of equal length. In Figure 1 the upperconnecting line is indicated by thevnumerals 13, 14, and 15. The centralportion 14 of this connecting line is connected at its ends by two uppercables 16, 17 to the sheering boards 3 and 4 respectively.

The central portion of the lower connecting .line 18 is connected in asimilar way by two ground cables 19 and 2O to the sheering boards 3and4. To the ends of the line 14 small floating bodies 21, 22 are,moreover, connected for lifting the back net.

Moreover, by the above-described Lipper and ground cables, the sheeringboards 3 and 4 are coupled in a substantially vertical plane by a wideupper cable 23. To this upper cable two large floating bodies 24 and 25are connected at such a mutua-l distance that when trailing the netthese floating bodies are located above or approximately above the twosheering boards as indicated in Figure 3'.

Thel sheering force driving' the boards away froml ea-ch other is nowreceived by the tension in the horizontal portion of the cable 23 whilethe updriving force of the iioating bodies 24 and 25l determines thetension in the downwardly running parts of this cable connecting thefloating bodiesA to the centres of thev sheering boards. The floatingbodies 24 and 25 are moreover connected by cables 32 to the upper backside of the sheering boards. v f

The Hoating bodies 24 and 25 are trailed by the branchy lines 26 of thetrailing lines 27 of the net.

The triangular portions formedv by the various lines ot' the skeletonarc closed in by a net in the usual way. Between the upper connectinglines 13, 14, 15 of the waists and the lower connecting line locatedunderneath a pouch shaped net is stretched. This pouch net 28 forms atransition between the front net and the two waists.

The points ot the line 14, to which the floating bodies 21 and 22 areattached, are connected by two lines 29 and 30 (see Figure 3) to thepoints of cable 23 under the floating bodies 24A and 25. The trapeziumrshaped plane between the lines 23, 14, 16 and 17 is iilled in by a net;equally the triangular planes formed by the lines 30 and 16y on the onehand andl 29 and 17 on the other hand, with the corresponding,verticalportions of cable 23. v

Finally, reference is directed to the wakening chain 31 which may bestretched in front of the ground cable between the sheeringv boards- Invthe net according to the invention it is only the resistance ot. a smallportion of the net itself that counteracts the sheering action of theboards; the resistance of the waists has no material influence thereon.

lli/Then the net is used for trawling on stony grounds then at the lowerside a pocket may be provided as shown in Figs. 4 and 5. The shape andthe connection of this pocket to the net appears sufficiently from thedrawings. It corresponds chiefly to the upper portion of the net. 33constitutes the ground cable which may be weighted or provided withrolls. The waists may be lifted by floating bodies 36. For trawlingher-rings the floating bodies 24 and 25 are connected by cables 34 tofloating bodies at the surface. The net is thereby lifted at the frontside and an opening is formed from the ground cable 33 to the horizontalupper cable 23. By shortening or lengthening the suspension lines 34 thedepth of the net under the water level may be adjusted.

Having now particularly described and ascertained the nature of our saidinvention and in what manner the same is to be performed, we decla-rethat what we claim is l. An improved trawlnet having two otterboards andtwo waists, the vertical central planes of which pass practicallythrough the connecting points of the net to the otterboards.

2. An improved trawlnet having two otterboards and two waists, t-hevertical eentral planes of which pass practically through the connectingpoints of the net to the otter'boards and each of which waists isdirectly connected by separate carrying lines to the otterboard locatedin front of it.

3. A trawlnct having two waists, each of which is directly connected tothe sheering board located in front of it, and interconnected by aconnecting line at the upper side and a connecting line at the lowerside of the net, while two points on each of these connecting lines areconnected by upper and ground cables respectively to the sheeringboards.

4. A trawlnet as claimed in claim 3 having 'floating bodies provided tothe two connecting points of the connecting line with the upper cables.

5. A trawlnet having two waists, the vertical central planes of whichare practically parallel to each other, and a wide upper cable stretchedbetween the sheering boards provided with two floating bodies at amutual distance practically equal to the distance of the sheering boardsat a normal trailing speed.

6. A trawlnet having two waists, each o-f which is directly connected byseparate carrying lines to a sheering board, and a wide upper cablestretched between the sheering boards provided with two floating bodiesat a mutual distance practically equal to the distance of the sheeringboards at a normal trailing speed.

7. A trawlnet having two waists, each of which is connected separatelyto a sheering board and interconnected at thel upper and the lower sideof the net whereas a wide upper cable is stretched between the sheer ingboards, provided with two floating bodies at a mutual distancecorresponding to the distance of the sheering boards at a normal speed'of trailing.

8. A trawlnet having two waists and means for connecting said waists tothe sheering boards and one tothe other, whereas the mutual connectinglines of the waists are connected to the sheering boards at the upperand lower side of the net by upperand ground ropes respectively, andwherein between the sheering boards of the net a second wide upper cableis stretched, to which two floating bodies are connected at a mutualdistance practically equal to the distance of the sheering boards at anormal trailing speed.

9. A trawlnet having two waists, lines for connecting said waists to thesheering boards and one to the other and lines for connecting two pointson the upper mutual connecting line of the waists to the sheeringboards, which two points are provided with floating bodies, whereas awide upper cable is stretched between the sheering boards having twofloating bodies at a mutual distance corresponding to the distance ofthe sheering boards at a normal trailing speed, and trailed by branchesof the net trailing ropes.

10. A trawlnet having a wide upper cable stretched between the sheeringboards, pro` vided with two Heating bodies, and two waists connected tothe sheering boards and interconnected by lines at the upper and thelower side of the net whereas each of two points of the upperinterconnecting line is connected to a sheering board and lto a point ofthe wide upper cable to which a floating body is attached.

11. A trawlnet having two waists, the vertical central planes of whichare practically parallel to each other and a wide upper cable stretchedbetween the sheering board and provided with two floating bodies trailedby branches of the net trailing ropes.

l2. A trawlnet having two waists, each of which is directly connected tothe sheering board located in front of it and two pocket shapedsecondary parts respectively located at the upper and at the lower sideof the main net the first one being limited at the. front side by a wideupper cable (23) stretched between the sheering boards and pro-videdwith two floating bodies (24, 25) suspended from surface floats (35) andtrailed by branches of the net trailing ropes, the latter limited at thefront side by a ground rope .13. A trawlnet having two waists, each ofwhich is directly ooniieotedv to the sheering board located in front ofit and two pocket shaped secondary parts respectively located f at theupper and at tlie lower side of the main net the lst one being limitedat the front side by a wide upper cable (23) stretched between thesheering boards and provided with two 4floating' bodies (24, 25)trailedby branch lines of the vnet trailing 10 ropes, the latter limitedat the front side by a grond rope (33') In testimony whereof we oursignatures; Y

ROELOF. .DE BOER. HENRI VVILLIJM DE VOGT.'

